Bloomberg's Jonathan Bernstein thinks President Trump will probably face a contested primary two years from now.

... it's ... quite likely that he will draw a fairly serious primary challeger in 2020. It's even possible it will rival the challenges to Presidents Jimmy Carter and Gerald Ford, which came close to defeating them for re-nomination.

Yes, he still has the support of most Republicans, although 80 percent same-party approval is nothing special, and his strong support is far less than that. Think about that 80 percent for a minute. Are those Republicans absolutely committed to voting for Trump in a primary election? Or is it possible to imagine a situation where a voter would approve of the job a president is doing, but also prefer another same-party replacement if one is available? ...

Pat Buchanan's challenge to President George H.W. Bush in 1992 is a good place to start this conversation. Bush began 1991 very popular, but fell steadily, dipping under the 50 percent mark late in the year. Buchanan, who had never before run for any office and who no one took seriously as a potential president at the time, then made plenty of noise in Republican Party primaries. While he didn't actually win any of them, Bush's approval ratings eventually dipped under the 30 percent mark.

The reason Trump won't be like Gerald Ford in 1976 or George H.W. Bush in 1992 is simple: Trump unquestionably represents what Republicanism is at this moment -- certainly more than any potential challenger. The GOP is a resentment-driven party, and there's no potential challenger who taps into that anger the way Trump does. There's no contest.

Ford and Poppy Bush didn't Unquestionably represent their party. They were the last two Republican presidents with greater ties to the GOP establishment than to the newer coalition of religious conservatives and resentment-driven suburban and exurban whites. It's no surprised that they faced reelection challenges from within the party.

Maybe Trump's voters will be disillusioned with the direction of the country in a couple of years, especially if the economy cools off or collapses (though nothing Robert Mueller is investigating will bother them) -- but it's likely that even an economic downturn won't faze them. George W. Bush retained considerable support within his party even in the waning days of his presidency, when nearly everyone else in America had abandoned him, because he wouldn't give up on the war, a stance GOP voters cheered because it infuriated liberals. Trump will be in a similar position in two years: We'll still hate him, so Republican voters will continue to embrace him.

Unless, of course, he finally makes the long-awaited pivot to the center, perhaps in reaction to a Democratic return to power after the midterms. But I don't see that happening. Republicans are still almost certain to hold the Senate, and Trump will still get most of his policy advice from Fox and Friends, so he'll remain a liberal-bashing hero to his base.

I suppose he might be impeached, but since there won't be 67 Democrats in the Senate ready to convict even in the best case, impeachment would probably make him more popular with the base.

No, he won't face a serious primary challenge. I don't know why this keeps coming up.